359 resultados para OFFSETS


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The present study was conducted to investigate whether ob- servers are equally prone to overlook any kinds of visual events in change blindness. Capitalizing on the finding from visual search studies that abrupt appearance of an object effectively captures observers' attention, the onset of a new object and the offset of an existing object were contrasted regarding their detectability when they occurred in a naturalistic scene. In an experiment, participants viewed a series of photograph pairs in which layouts of seven or eight objects were depicted. One object either appeared in or disappeared from the layout, and participants tried to detect this change. Results showed that onsets were detected more quickly than offsets, while they were detected with equivalent ac- curacy. This suggests that the primacy of onset over offset is a robust phenomenon that likely makes onsets more resistant to change blindness under natural viewing conditions.

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Since 1995 the eruption of the andesitic Soufrière Hills Volcano (SHV), Montserrat, has been studied in substantial detail. As an important contribution to this effort, the Seismic Experiment with Airgunsource-Caribbean Andesitic Lava Island Precision Seismo-geodetic Observatory (SEA-CALIPSO) experiment was devised to image the arc crust underlying Montserrat, and, if possible, the magma system at SHV using tomography and reflection seismology. Field operations were carried out in October–December 2007, with deployment of 238 seismometers on land supplementing seven volcano observatory stations, and with an array of 10 ocean-bottom seismometers deployed offshore. The RRS James Cook on NERC cruise JC19 towed a tuned airgun array plus a digital 48-channel streamer on encircling and radial tracks for 77 h about Montserrat during December 2007, firing 4414 airgun shots and yielding about 47 Gb of data. The main objecctives of the experiment were achieved. Preliminary analyses of these data published in 2010 generated images of heterogeneous high-velocity bodies representing the cores of volcanoes and subjacent intrusions, and shallow areas of low velocity on the flanks of the island that reflect volcaniclastic deposits and hydrothermal alteration. The resolution of this preliminary work did not extend beyond 5 km depth. An improved three-dimensional (3D) seismic velocity model was then obtained by inversion of 181 665 first-arrival travel times from a more-complete sampling of the dataset, yielding clear images to 7.5 km depth of a low-velocity volume that was interpreted as the magma chamber which feeds the current eruption, with an estimated volume 13 km3. Coupled thermal and seismic modelling revealed properties of the partly crystallized magma. Seismic reflection analyses aimed at imaging structures under southern Montserrat had limited success, and suggest subhorizontal layering interpreted as sills at a depth of between 6 and 19 km. Seismic reflection profiles collected offshore reveal deep fans of volcaniclastic debris and fault offsets, leading to new tectonic interpretations. This chapter presents the project goals and planning concepts, describes in detail the campaigns at sea and on land, summarizes the major results, and identifies the key lessons learned.

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Introduction: In an attempt to reduce stress shielding in the proximal femur multiple new shorter stem design have become available. We investigated the load to fracture of a new polished tapered cemented short stem in comparison to the conventional polished tapered Exeter stem. Method: A total of forty-two stems, twenty-one short stems and twenty-one conventional stems both with three different offsets were cemented in a composite sawbone model and loaded to fracture. Results: study showed that femurs will break at a significantly lower load to failure with a shorter compared to conventional length Exeter stem. Conclusion: This Both standard and short stem design are safe to use as the torque to failure is 7–10 times as much as the torques seen in activities of daily living.

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This paper presents a framework for synchronising multiple triggered sensors with respect to a local clock using standard computing hardware. Providing sensor measurements with accurate and meaningful timestamps is important for many sensor fusion, state estimation and control applications. Accurately synchronising sensor timestamps can be performed with specialised hardware, however, performing sensor synchronisation using standard computing hardware and non-real-time operating systems is difficult due to inaccurate and temperature sensitive clocks, variable communication delays and operating system scheduling delays. Results show the ability of our framework to estimate time offsets to sub-millisecond accuracy. We also demonstrate how synchronising timestamps with our framework results in a tenfold reduction in image stabilisation error for a vehicle driving on rough terrain. The source code will be released as an open source tool for time synchronisation in ROS.

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"Taxation law can be an incredibly complex subject to absorb, particularly when time is limited. Written specifically for students, Principles of Taxation Law 2014 brings much needed clarity to this area of law. Utilising many methods to make this often daunting subject achievable, particular features of the 2014 edition include: seven parts: overview and structure, principles of income, deductions and offsets, timing issues, investment and business entities, tax avoidance and administration, and indirect taxes; clearly structured chapters within those parts grouped under helpful headings;flowcharts, diagrams and tables, end of chapter practice questions, and case summaries; an appendix containing all of the up to date and relevant rates; and the online self-testing component mentor, which provides questions for students of both business and law. Every major aspect of the Australian tax system is covered, with chapters on topics such as goods and services tax, superannuation, offsets, partnerships, capital gains tax, trusts, company tax and tax administration.All chapters have been thoroughly revised"-- Publishers website

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Synchronization issues pose a big challenge in cooperative communications. The benefits of cooperative diversity could be easily undone by improper synchronization. The problem arises because it would be difficult, from a complexity perspective, for multiple transmitting nodes to synchronize to a single receiver. For OFDM based systems, loss of performance due to imperfect carrier synchronization is severe, since it results in inter-carrier interference (ICI). The use of space-time/space-frequency codes from orthogonal designs are attractive for cooperative encoding. But orthogonal designs suffer from inter-symbol interference (ISI) due to the violation of quasi-static assumption, which can arise due to frequency- or time-selectivity of the channel. In this paper, we are concerned with combating the effects of i) ICI induced by carrier frequency offsets (CFO), and ii) ISI induced by frequency selectivity of the channel, in a cooperative communication scheme using space-frequency block coded (SFBC) OFDM. Specifically, we present an iterative interference cancellation (IC) algorithm to combat the ISI and ICI effects. The proposed algorithm could be applied to any orthogonal or quasi-orthogonal designs in cooperative SFBC OFDM schemes.

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The superconducting (or cryogenic) gravimeter (SG) is based on the levitation of a super­conducting sphere in a stable magnetic field created by current in superconducting coils. Depending on frequency, it is capable of detecting gravity variations as small as 10-11ms-2. For a single event, the detection threshold is higher, conservatively about 10-9 ms-2. Due to its high sensitivity and low drift rate, the SG is eminently suitable for the study of geodynamical phenomena through their gravity signatures. I present investigations of Earth dynamics with the superconducting gravimeter GWR T020 at Metsähovi from 1994 to 2005. The history and key technical details of the installation are given. The data processing methods and the development of the local tidal model at Metsähovi are presented. The T020 is a part of the worldwide GGP (Global Geodynamics Project) network, which consist of 20 working station. The data of the T020 and of other participating SGs are available to the scientific community. The SG T020 have used as a long-period seismometer to study microseismicity and the Earth s free oscillation. The annual variation, spectral distribution, amplitude and the sources of microseism at Metsähovi were presented. Free oscillations excited by three large earthquakes were analyzed: the spectra, attenuation and rotational splitting of the modes. The lowest modes of all different oscillation types are studied, i.e. the radial mode 0S0, the "football mode" 0S2, and the toroidal mode 0T2. The very low level (0.01 nms-1) incessant excitation of the Earth s free oscillation was detected with the T020. The recovery of global and regional variations in gravity with the SG requires the modelling of local gravity effects. The most important of them is hydrology. The variation in the groundwater level at Metsähovi as measured in a borehole in the fractured bedrock correlates significantly (0.79) with gravity. The influence of local precipitation, soil moisture and snow cover are detectable in the gravity record. The gravity effect of the variation in atmospheric mass and that of the non-tidal loading by the Baltic Sea were investigated together, as sea level and air pressure are correlated. Using Green s functions it was calculated that a 1 metre uniform layer of water in the Baltic Sea increases the gravity at Metsähovi by 31 nms-2 and the vertical deformation is -11 mm. The regression coefficient for sea level is 27 nms-2m-1, which is 87% of the uniform model. These studies are associated with temporal height variations using the GPS data of Metsähovi permanent station. Results of long time series at Metsähovi demonstrated high quality of data and correctly carried out offsets and drift corrections. The superconducting gravimeter T020 has been proved to be an eminent and versatile tool in studies of the Earth dynamics.

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"Taxation law can be an incredibly complex subject to absorb, particularly when time is limited. Written specifically for students, Principles of Taxation Law 2016 brings much needed clarity to this area of law. Utilising many methods to make this often daunting subject achievable, particular features of the 2016 edition include: - seven parts: overview and structure, principles of income, deductions and offsets, timing issues, investment and business entities, tax avoidance and administration, and indirect taxes; - clearly structured chapters within those parts grouped under helpful headings; - flowcharts, diagrams and tables, end of chapter practice questions, and case summaries; - an appendix containing all of the up to date and relevant rates; and - the online self-testing component mentor, which provides questions for students of both business and law; Every major aspect of the Australian tax system is covered, with chapters on topics such as goods and services tax, superannuation, offsets, partnerships, capital gains tax, trusts, company tax, tax administration and state taxes."--Publisher Website

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This paper describes a concept for a collision avoidance system for ships, which is based on model predictive control. A finite set of alternative control behaviors are generated by varying two parameters: offsets to the guidance course angle commanded to the autopilot and changes to the propulsion command ranging from nominal speed to full reverse. Using simulated predictions of the trajectories of the obstacles and ship, compliance with the Convention on the International Regulations for Preventing Collisions at Sea and collision hazards associated with each of the alternative control behaviors are evaluated on a finite prediction horizon, and the optimal control behavior is selected. Robustness to sensing error, predicted obstacle behavior, and environmental conditions can be ensured by evaluating multiple scenarios for each control behavior. The method is conceptually and computationally simple and yet quite versatile as it can account for the dynamics of the ship, the dynamics of the steering and propulsion system, forces due to wind and ocean current, and any number of obstacles. Simulations show that the method is effective and can manage complex scenarios with multiple dynamic obstacles and uncertainty associated with sensors and predictions.

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Separated local field (SLF) spectroscopy is a powerful technique to measure heteronuclear dipolar couplings. The method provides site-specific dipolar couplings for oriented samples such as membrane proteins oriented in lipid bilayers and liquid crystals. A majority of the SLF techniques utilize the well-known Polarization Inversion Spin Exchange at Magic Angle (PISEMA) pulse scheme which employs spin exchange at the magic angle under Hartmann-Hahn match. Though PISEMA provides a relatively large scaling factor for the heteronuclear dipolar coupling and a better resolution along the dipolar dimension, it has a few shortcomings. One of the major problems with PISEMA is that the sequence is very much sensitive to proton carrier offset and the measured dipolar coupling changes dramatically with the change in the carrier frequency. The study presented here focuses on modified PISEMA sequences which are relatively insensitive to proton offsets over a large range. In the proposed sequences, the proton magnetization is cycled through two quadrants while the effective field is cycled through either two or four quadrants. The modified sequences have been named as 2(n)-SEMA where n represents the number of quadrants the effective field is cycled through. Experiments carried out on a liquid crystal and a single crystal of a model peptide demonstrate the usefulness of the modified sequences. A systematic study under various offsets and Hartmann-Hahn mismatch conditions has been carried out and the performance is compared with PISEMA under similar conditions.

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In uplink orthogonal frequency division multiple access (OFDMA) systems, multiuser interference (MUI) occurs due to different carrier frequency offsets (CFO) of different users at the receiver. In this paper, we present a minimum mean square error (MMSE) based approach to MUI cancellation in uplink OFDMA. We derive a recursion to approach the MMSE solution. We present a structure-wise and performance-wise comparison of this recursive MMSE solution with a linear PIC receiver as well as other detectors recently proposed in the literature. We show that the proposed recursive MMSE solution encompasses several known detectors in the literature as special cases.

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The present work explores the temperature dependent transport behavior of n-InN nanodot/p-Si(100) heterojunction diodes. InN nanodot (ND) structures were grown on a 20 nm InN buffer layer on p-Si(100) substrates. These dots were found to be single crystalline and grown along 001] direction. The junction between these two materials exhibits a strong rectifying behavior at low temperatures. The average barrier height (BH) was determined to be 0.7 eV from current-voltage-temperature, capacitance-voltage, and flat band considerations. The band offsets derived from built-in potential were found to be Delta E-C=1.8 eV and Delta E-V=1.3 eV and are in close agreement with Anderson's model. (C) 2010 American Institute of Physics. doi:10.1063/1.3517489]

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In uplink orthogonal frequency division multiple access (OFDMA) systems, multiuser interference (MUI) occurs due to different carrier frequency offsets (CFO) of different users at the receiver. In this paper, we present a multistage linear parallel interference cancellation (LPIC) approach to mitigate the effect of this MUI in uplink OFDMA. The proposed scheme first performs CFO compensation (in time domain), followed by K DFT operations (where K is the number of users) and multistage LPIC on these DFT outputs. We scale the MUI estimates by weights before cancellation and optimize these weights by maximizing the signal-to-interference ratio (SIR) at the output of the different stages of the LPIC. We derive closed-form expressions for these optimum weights. The proposed LPIC scheme is shown to effectively cancel the MUI caused by the other user CFOs in uplink OFDMA.

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The similar to 2500 km long Himalayan arc has experienced three large to great earthquakes of M-w 7.8 to 8.4 during the past century, but none produced surface rupture. Paleoseismic studies have been conducted during the last decade to begin understanding the timing, size, rupture extent, return period, and mechanics of the faulting associated with the occurrence of large surface rupturing earthquakes along the similar to 2500 km long Himalayan Frontal Thrust (HFT) system of India and Nepal. The previous studies have been limited to about nine sites along the western two-thirds of the HFT extending through northwest India and along the southern border of Nepal. We present here the results of paleoseismic investigations at three additional sites further to the northeast along the HFT within the Indian states of West Bengal and Assam. The three sites reside between the meizoseismal areas of the 1934 Bihar-Nepal and 1950 Assam earthquakes. The two westernmost of the sites, near the village of Chalsa and near the Nameri Tiger Preserve, show that offsets during the last surface rupture event were at minimum of about 14 m and 12 m, respectively. Limits on the ages of surface rupture at Chalsa (site A) and Nameri (site B), though broad, allow the possibility that the two sites record the same great historical rupture reported in Nepal around A.D. 1100. The correlation between the two sites is supported by the observation that the large displacements as recorded at Chalsa and Nameri would most likely be associated with rupture lengths of hundreds of kilometers or more and are on the same order as reported for a surface rupture earthquake reported in Nepal around A.D. 1100. Assuming the offsets observed at Chalsa and Nameri occurred synchronously with reported offsets in Nepal, the rupture length of the event would approach 700 to 800 km. The easternmost site is located within Harmutty Tea Estate (site C) at the edges of the 1950 Assam earthquake meizoseismal area. Here the most recent event offset is relatively much smaller (<2.5 m), and radiocarbon dating shows it to have occurred after A.D. 1100 (after about A.D. 1270). The location of the site near the edge of the meizoseismal region of the 1950 Assam earthquake and the relatively lesser offset allows speculation that the displacement records the 1950 M-w 8.4 Assam earthquake. Scatter in radiocarbon ages on detrital charcoal has not resulted in a firm bracket on the timing of events observed in the trenches. Nonetheless, the observations collected here, when taken together, suggest that the largest of thrust earthquakes along the Himalayan arc have rupture lengths and displacements of similar scale to the largest that have occurred historically along the world's subduction zones.

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In this paper, we investigate cooperative OFDM communications using amplify-and-forward (AF) protocol at the relays, in the presence of imperfect timing synchronization. In most studies on cooperative communications, perfect time synchronization among cooperating nodes is assumed. In practice, however, due to imperfect time synchronization, orthogonality among the subcarriers of the different nodes' signals at the destination receiver can be lost, causing inter-symbol interference (ISI). In this paper, we derive analytical expressions for the average SINR at the DFT output at the destination as a function of timing offset in cooperative OFDM with AF protocol, and illustrate the SINR degradation as a function of the timing offset. We also present an interference canceling (IC) receiver to mitigate the effects of ISI when there is timing offset. We show that the proposed IC receiver achieves improved BER performance even when timing offsets are large.